Knock, knock, who's there?

[tamson]

Is "rod knock" a problem associated with type 4 engines, or is it more of a problem with earlier marks? My engine (2ltr CU) has developed a knock that I'm trying to get to the bottom of and it's driving me mad! I've listened to umpteen videos on YouTube of knocking engines and although they all sound more or less the same, none of them seems to sound like mine! Can anyone recommend a procedure for narrowing down engine knocks? Thanks!

[diabolov]

Hi Tamson,


Use a long bit of metal, like a long screwdriver, and use it like as a stethoscope to narrow down where the knock is coming from and the probable cause.

Regards

Mark

[dave friday]

one check is to accelerate then take your foot off and listen for a nock/rattle

[Ian Hulley]

The last aircold engine with a bad knock that I heard had lost a valve guide from the head and had been happily trying to hammer it around the combustion chamber

Ian

[tamson]

Hi guys thanks for advice. It's interesting that you mentioned valve guide as I recently (last September) had to replace a valve and guide as for some bizarre reason it snapped just above the collets. Quite lucky really as it meant the valve didn't damage the piston. It was literally about 5mm from the tip of the exhaust valve. But perhaps it's damaged the head and the guide is coming loose! . The knock only appears after the engine is thoroughly warmed - after say a good 20minute drive - and is fairly prominent but not constant and only at idle.

[123-jn]

I wonder what your oil pressure is like? I had an old transit 1.6 ohv and once it was warm it used to have a rod knock due to low oil pressure especially at tickover, with some revs it went away as the oil pressure increased. Eventually the oil light started to flash with the knock and I knew its days were numbered. These engines are prone to throw rods in these conditions.

[tamson]

I have a compressor tester for the cylinder heads, am I right in thinking I can hook it up to check oil pressure too?

[Ian Hulley]

I have a compressor tester for the cylinder heads, am I right in thinking I can hook it up to check oil pressure too?

Only if you have the correct adaptor (M10 x 1.00mm if I remember correctly but that's on a WBXer engine)

Ian

[tamson]

Hi Ian, I checked the oil pressure, hooked up the gauge and it went straight to 50psi and stayed there, needle totally stable.

[tamson]

https://youtu.be/t07QP-rK7-0" onclick="window.open(this.href);return false; Here is a link to a video I took of it last night. This is after 20 mins idling.

[tamson]

https://youtu.be/9ui--Phy-hM" onclick="window.open(this.href);return false; This is it cold upon start up. No knock.

[tamson]

https://youtu.be/Wcgo0cmUFGQ" onclick="window.open(this.href);return false; This is how it sounds after a good 40mile round trip. Sorry for all the boring videos!

[mbcamper]

What was the engine oil pressure after the engine was up to temperature?

When the engine is cold you will get a higher pressure until the engine gets warm and thins the oil. It's at this point that the pressure needs to be measured and compared with the expected values.

[tamson]

Okay I'll check it tonight, I'll give it a good run then have a look. I was thinking about hooking up the gauge before I drive it rather than trying to screw it in when hot, does that sound safer?

[kevtherev]

I let mine tick over on the drive with the gauge plugged in